题解 | #n的阶乘#

#include<iostream>
using namespace std;

long long cal(int n){
	if(n==0){
		return 1; 
	}
	return n*cal(n-1);
}

int main(){
	int n;
	while(scanf("%d",&n)!=EOF){
		printf("%lld\n",cal(n));
	} 
}